The present invention relates generally to processing timestamps in communication packets and, more particularly, to processing timestamps in communication networks that include media access control security.
It may be advantageous in a networked system for devices in the network to include timestamp information in some communication packets. The timestamp information may be indicative of when a packet is transmitted or received by one of the devices. The timestamp information may be used, for example, to synchronize clocks between devices in the network. The timestamp information may also be used for operation, administration, and maintenance functions in the network. The electronics industry has developed several standard protocols that use timestamped packets, for example, the Precision Time Protocol (PTP) of IEEE Std. 1588 and ITU-T Recommendation Y.1731 on Internet protocol aspects—Operation, administration and maintenance.
It may also be advantageous to secure at least some communication in a network to avoid interception of information or disruption of network operations. Some information may be protected by encrypting the information at its source and decrypting it at its destination. Other information may be protected by inclusion of a check value or digital signature that allows a receiving device to confirm that the information has not been altered since it was sent from a transmitting device. One protocol for increasing network security is Media Access Control (MAC) Security of IEEE Std. 802.1AE.
It may be further advantageous for a network to provide both timestamp information and increased security. However, security measures may interfere with timestamp information by, for example, increasing uncertainty with respect to the timing information, which in many cases should also be subject to the security measures. Reducing effects of security measures on timing information may be difficult, however, particularly without unduly reducing bandwidth of a communication system.